As the war in Ukraine has unfolded over the past two years, a seemingly endless series of videos have emerged from the battlefield, depicting drones—of various shapes and configurations—targeting and destroying personnel and equipment on both sides. Often, these systems are used at the microtactical level, to target individual soldiers and vehicles, and thus cannot realistically be defeated by current air defense systems. At the same time, across Iraq, Syria, Jordan, and the Red Sea, we are seeing the proliferation of one-way suicide drones being used against US, allied, and partner forces. To engage and destroy these drones, US forces are mostly reliant on two tools—shipborne weapons from a family known as Standard Missiles and Close-In Weapon Systems, which are essentially gatling guns attached to radars that throw up a wall of lead to defeat closing aerial threats.

The Phalanx Close-In Weapon System, with a maximum effective range of 1,500 meters and firing seventy-five rounds per second, has proved effective in countering modern drones. Its land-based variant, the well-known C-RAM, was similarly effective during the Afghanistan War against a variety of indirect fire. However, it is confined to a stationary defensive role, guarding warships and bases. On the modern battlefield, where drones are becoming prolific, there is a major gap that needs to be filled in counterdrone weapons systems.

The current US systems, and those in development, are effective under some conditions, but with the increased proliferation of cheap, lethal drones—and the threat of drone swarms looming on the horizon—having a system that can engage rapidly with lethal accuracy, in an extremely short period of time, is critical to defeating multiple fast-moving targets in close proximity.

The US Army should invest in modernizing its air defense artillery forces, to include dedicated antiaircraft artillery (AAA) batteries that are capable of defeating the threat posed by small unmanned aircraft systems (sUAS). Specifically, the service should reintroduce legacy-style gatling gun systems and work to field new systems rooted in the proven concept of the wall of lead.

The sUAS Threat

Many of the sUAS already present on today’s battlefield are so small that they can be carried in one hand by their operators. In Ukraine, drone operators are working in coordinated hunter-killer teams, where one reconnaissance drone identifies targets for a team of attack drones to destroy. In a not-so-distant future, these hunter-killer teams could be further developed into advanced swarms that could operate semiautonomously, with a human only in the loop to approve targets prior to engagement, or even entirely autonomously of human operators. Many of the drones currently being weaponized are commercial, off-the-shelf systems designed for civilian use and, importantly, some are designed specifically for racing. These racing drones are extremely fast and nimble, often mounted with multiple rotors allowing them to rapidly move omnidirectionally. They are extremely hard to pinpoint and target, as they can move in an unpredictable, nearly insect-like manner in order to close with their prey.

After closing the distance, these deceptively small drones are capable of dealing devastating damage. Whether individual soldiers hiding out in craters and trenches or heavily armored T-series tanks, a single drone can find, fix, and finish targets with precision and efficiency.

Neither side of the Russo-Ukraine conflict has created a fully successful counter to this threat. Jamming systems have been effective, but often require a line of sight to cut or control the signals between a drone and its operator. In several documented instances however, these drones have been successfully downed by shotguns, machine-gun fire, and in at least one instance, a homemade gatling gun composed of a dozen AK-74s. The Gepard AAA system, given to the Ukrainians by Germany, has been highly effective in downing larger drones, such as the Iranian Shahed series that Russia has purchased and is now producing itself.

What this means is that on both sides of the war in Ukraine, the combatants have been forced to improvise and adapt under austere conditions—and have found success in simply throwing up walls of lead to down sUAS. This discovery has implications for the Army, the US armed service that will most likely face the brunt of the sUAS threat in a future large-scale combat environment. Put simply, it does not currently maintain a system that can effectively defeat these drones along the front lines.

M-SHORAD and Avenger Systems: Gaps in the Air Defense Inventory

The two current tactical air defense systems fielded by the US Army are the AN/TWQ-1 Avenger, which is mounted on a Humvee, and the new M-SHORAD (Maneuver–Short Range Air Defense) system mounted on the Stryker armored fighting vehicle. However, neither is suited for tactical and operational air defense in support of maneuver elements on the battlefield.

The first and most obvious issue is that both of these systems rely primarily on surface-to-air missiles to defeat targets. For targeting small, cheaply produced and converted sUAS, expensive missiles are simply not a cost-effective method of destruction. Additionally, these systems can only fire a small number of missiles (single digits for both platforms) before they are required to reload.

The M-SHORAD also mounts a single-barrel, 30-millimeter chain gun, similar to that on the Apache gunship. Even this weapon, though, is not suited to tracking and targeting small, fast-moving objects mounted with hand grenades, for example, or converted warheads for rocket-propelled grenades. It does not have the rate of fire to be able to throw up the mass of bullets necessary to defeat the aerial maneuvers of a drone, and certainly not if there are several of them. Footage in Ukraine shows that soldiers on both sides have attempted to use their rifles to defeat these drones, and they are rarely successful. It is simply too hard to hit such a small target with single accurate rounds.

Furthermore, these assets were not designed to be operated on or near front lines. Enemy drones operating in a swarm, with some dedicated to conducting suppression of enemy air defenses, could easily defeat an Avenger mounted on an unarmored Humvee or an M-SHORAD mounted on the lightly armored Stryker, only rated to stop 14.5-millimeter rounds. Neither could withstand direct hits, or potentially even near misses, from explosive-laden drones that have demonstrated the capability to destroy Russian tanks.

Additionally, as both these systems are wheeled, rather than tracked, they lack the same maneuverability and mobility of tracked vehicles, particularly in muddy terrain—like that found in Eastern Europe in the spring and in the Indo-Pacific region during rainy seasons.

It is important to note that these systems are both extremely valuable air defense assets that should continue to serve in rear-area aerial security roles. However, they do not offer the capability and protection required to counter the growing threat from sUAS. Nothing in the current US air defense arsenal has the protection necessary to operate near the front line and the fires capability to destroy swarms of cheap drones.

What’s Old is New Again

The US Army was not always in such a predicament. In fact, until the mid-2000s, the service maintained an armored vehicle that could provide air defense along the forward line of troops. The M6 Linebacker was a modified Bradley Fighting Vehicle that simply replaced its turret-mounted TOW missile launcher with a launcher that carried Stinger missiles. The M6 also kept the Bradley’s organic 25-millimeter chain gun for additional air and ground targeting capability. The M6 was fully capable of operating in a mechanized formation as an armored air guard that could maneuver and provide constant overhead protection simultaneously. However, similar to the M-SHORAD system, the M6 was also only equipped with a single-barrel cannon that fires too slowly to make it effective against small drones.

Thus, we must look further back into history to the predecessor of the M6, the M163 Vulcan Air Defense System. The M163 was an unsubtle bullet hose. It was little more than an M113 armored personnel carrier with a 20-millimeter Vulcan rotary cannon, similar to those mounted on the F-16 and A-10, inelegantly slapped onto the top. It was capable of firing a whopping three thousand rounds per minute in burst mode or one thousand rounds a minute cyclic mode, with rounds set to detonate at 1,800 meters.

The M163 was sold to the Israel Defense Forces, who modified the design, and created the improved Machbet variant, which added four Stinger missile launch tubes to the Vulcan cannon for targeting a variety of threats.

The M163 had its major drawbacks too. It lacked an organic radar system and relied on human gunnery to acquire and target enemy air assets. The M113 vehicle it was based on is also limited, primarily in the fact that it is a more lightly armored personnel carrier, not designed to withstand the same level of fire as tanks or the more modern Bradley. A new system, the M247 Sergeant York, was planned for development in the 1970s and early 1980s, but the program was an utter debacle and was scrapped in 1985.

Both of these systems once in the US Army inventory, the M6 and the M163, offered something missing today. They both had the advantage of being tracked vehicles, for instance. But each also had its deficiencies. The M6 had the armor but not the right firepower, while the M163 lacked the armor but packed the right punch, particularly in later variants. If the strengths of these two systems could be married, however, there could be an air defense vehicle with both the armor and firepower to operate alongside maneuver formations and able to defeat both sUAS and larger threats such as helicopters.

The Solution

The US Army must invest in a mobile air defense system with the capability to effectively defeat the enemy sUAS threat, while also retaining the protection and maneuverability to operate in frontline areas.

The solution does not need to be a revolutionary system. Nor should it be. The threat from sUAS is here now, and a project that spends the next decade in research and development will not counter the present threat. The relatively simple and much more low-cost solution is to use older-model Bradley Fighting Vehicles no longer in active US service—there are nearly three thousand currently sitting in storage—and convert them to basic but functional AAA systems. These conversions would not require the invention of an entirely new vehicle platform and would only require an off-the-shelf existing system such as the Close-In Weapon System or the development of a similar, but more tailored, AAA system. Having such a system mounted on a vehicle that can operate under the dangerous conditions of frontline combat and is able to withstand all but a direct hit from an antiarmor-equipped drone or other weapons system, could be the difference between life and death for US soldiers in a conflict in the very near future.

Without such a system available, US ground forces will be vulnerable to attack from sUAS and will have no effective defense other than firing wildly into the air as an untold number of now deceased combatants in Ukraine did, to no avail.

Cadet Benjamin Phocas is a Defense and Strategic Studies major at the United States Military Academy at West Point.

Major Peter Mitchell is an air defense officer and Strategic Studies instructor at the United States Military Academy at West Point.

The views expressed are those of the authors and do not reflect the official position of the United States Military Academy, Department of the Army, or Department of Defense.

Image credit: Ben Santos, US Department of Defense Public Affairs